Packaging film, package, package/packed product unit and use for a packaging film

ABSTRACT

The invention concerns a packaging film comprising or consisting of a layer system with a barrier layer preventing oxygen penetration, an adhesion improvement layer adjacent to the barrier layer and an oxygen scavenger layer adjacent to the adhesion improvement layer. The invention also concerns a packaging, a packaging-packed product unit and the use of a packaging film.

The invention concerns a laminated packaging film comprising or consisting of a layer system which has a barrier layer preventing oxygen penetration and an oxygen scavenger layer.

Furthermore, the invention concerns a packaging produced using such a packaging film, in particular a blister pack.

Furthermore, the invention concerns a packaging-packed product unit using the packaging described above.

In addition, the invention concerns the use of a packaging film described above for producing a packaging.

It is known that oxygen can accelerate the spoiling of foodstuffs and lead to function disruption of other products, in particular pharmaceutical or cosmetic products. Oxygen firstly has a direct oxidation effect on particular product constituents and in addition in many cases allows the growth of aerobic micro-organisms.

To prevent the negative consequences of oxygen effect on the packed product, it is known to equip packaging films with a so-called oxygen scavenger layer. The function of the scavengers which are present in such a layer is firstly to eliminate any residual oxygen content remaining in the head space on packing of the product, and the oxygen dissolved in the packed product, as quickly as possible. In addition, the task of oxygen scavengers is to absorb the oxygen permeating through the packaging and as a result extend the conservation time of the oxidation-sensitive packed product.

WO 2007/051860 A1 discloses a lacquer material for production of an oxygen scavenger layer, wherein the lacquer material comprises a matrix of partly organic polymers and a component (scavenger) which, after suitable triggering, destroys oxygen.

In practice the production of a packaging film using such a lacquer material causes difficulties as delamination phenomena always occur. In addition, the oxygen bonding capacity of such a packaging film with an oxygen scavenger layer is in need of improvement.

The invention is therefore based on the object of proposing a robust and durable packaging film which is suitable for practical use and comprising an oxygen scavenger layer. Preferably, the oxygen bonding capacity of the packaging film is optimised. Furthermore, the object is also to propose a correspondingly optimised packaging and a correspondingly optimised packaging-packed product unit.

With regard to the packaging film, the object is achieved by the construction of a layer system which comprises firstly a barrier layer active against oxygen, an adhesion improvement layer adjacent to the barrier layer and an oxygen scavenger layer adjacent to the adhesion improvement layer. It is also part of the invention that the packaging film consists exclusively of such a layer system or the layer system has at least one further layer in the finished packaging film.

With regard to the packaging, the object is achieved by the use of at least one packaging film formed according to the concept of the invention and the use of a packaging film to produce a packaging. Preferably, the packaging is a foodstuff packaging, a pharmaceutical or a cosmetic packaging.

With regard to the packaging-packed product unit, the object is achieved by the use of a packaging surrounding at least one packed product, which packaging is produced using at least one packaging film formed according to the concept of the invention.

The invention is based on the concept of providing a layer system with a barrier layer which is active against oxygen, in particular an aluminium-containing layer, wherein the task of the barrier layer is to prevent or at least minimise the permeation of oxygen from the environment into the inner volume of the packaging to the packed product, with the consequence that an oxygen scavenger layer which is also provided in the layer system remains able to function, i.e. eliminate oxygen, for as long a time as possible. Here it is preferred that the oxygen scavenger layer is arranged on the side of the barrier layer facing the packed product. To minimise delamination phenomena and consequently to obtain a robust packaging film which is suitable for practical use, with a packaging film formed according to the concept of the invention it is proposed that the barrier layer and the oxygen scavenger layer hold between them an adhesion improvement layer in a sandwich form. In other words the adhesion improvement layer forms the bonding element toward the barrier layer which is active against oxygen and the oxygen scavenger layer having at least one oxygen scavenging component. Surprisingly, the use of the adhesion improvement layer between the barrier layer and the oxygen scavenger layer not only increases the robustness of the packaging film but the packaging film, in comparison with a packaging film without adhesion improvement layer, has substantially improved oxygen eliminating (scavenging) properties (synergy effect). Thus it could be proven in tests that the oxygen absorption capacity of a packaging film was improved by the use of an adhesion improvement layer from 108 cm³O₂/g to 119 cm³O₂/g, i.e. by around 10%. The weight figure in grammes [g] relates to the oxygen scavenger layer. By this surprising additional effect, with a packaging film formed according to the concept of the invention, the packed products can be stored for a longer period without this having a negative influence on the product properties.

An embodiment of the packaging film in which the oxygen scavenger layer is formed from a lacquer material is particularly advantageous. The lacquer material can be applied to the adhesion improvement layer in various ways. It is thus conceivable that the lacquer material is printed onto the oxygen scavenger layer, or alternatively cast for example by means of a lacquer material curtain, sprayed or applied by blade or brush.

In a refinement of the invention it is advantageously proposed that the lacquer material is formed as disclosed in WO 2007/051860 A1. In relation to possible embodiments of the lacquer material therefore WO 2007/051860 A1 is considered disclosed as part of the disclosure content of the present application, in particular with the consequence that at least one arbitrary feature of the present application can be combined with at least one arbitrary feature of WO 2007/051860 A1 and claimed. Particularly preferably the matrix is created using at least one silane which contains a group which is accessible to an organic polymerisation, addition or condensation reaction, particularly preferably a vinyl, allyl, methacryl or glycidyl group. In addition or alternatively the matrix can be produced using a metal alkoxide which is preferably selected from the alkoxides of aluminium, zirconium, titanium or tin. In addition, the lacquer material preferably comprises a component selected from components which scavenge oxygen after suitable triggering, in particular actinic radiation. Preferably, the oxygen scavenging component is bonded covalently in the matrix. Particularly preferably, the oxygen scavenging component is a silane-bonded residue, whereby it is further preferred if the oxygen scavenging component is an organic residue which contains a cyclic olefin. Particularly preferably, the triggering takes place using actinic radiation, preferably in the presence of a photo-sensitizer.

With regard to the formation of the adhesion improvement layer, there are various possibilities. It is conceivable that the adhesion improvement layer is produced by surface treatment of the barrier layer directly on the barrier layer. In addition or alternatively the adhesion layer can be applied to the barrier layer as a separate layer, in particular printed or laminated on. Particularly preferred is an embodiment in which the adhesion improvement layer is formed as a polyurethane primer layer and/or an acrylic resin primer layer and/or an ethylene acrylic acid polymer layer. Particularly preferably this is an extrusion-coated polymer layer. In addition or alternatively the adhesion improvement layer can be an ionomer resin layer, for example Surlyn® by DuPont. A further possibility for forming the adhesion improvement layer is to construct the adhesion improvement layer by plasma treatment or by corona treatment of the barrier layer. In addition or alternatively it is conceivable to structure the adhesion improvement layer as a PVD (physical vacuum deposition) layer and/or as a sol-gel layer. A PVD layer can for example be formed by electron beam vapour deposition or resistance heating or inductive heating of materials to be vaporised i.e. corresponding target materials such as SiO_(x), wherein x is a figure from 1.1 to 2.0, or as an Al₂O₃ layer. For a sol-gel layer, this is preferably a coating of a cross-linked organo-functional silane which is obtained with a metal compound, for example by hydrolytic condensation, where applicable in the presence of a condensation catalyst. In some cases non-crosslinkable organo-functional silanes can be contained, and where applicable one or more non-volatile oxides. An organic prepolymer is added to the hydrolytic condensate. The resulting coating solution can be applied to a substrate and then hardened. This process constructs an organic network and by way of correspondingly derivitised silicic acid esters, additional organic groups can be incorporated which serve firstly for functionalisation and secondly for formation of defined organic polymer systems. Further possibilities, already cited in some cases, for forming the adhesion improvement layer include the production of the adhesion improvement layer on a copolymer acrylate basis preferably as a coating, and/or on a copolymer ethylene acrylic acid basis preferably as a coating, and/or on a cellulose nitrate basis preferably as a lacquer, and/or on a polyester basis preferably as a lacquer, and/or on the basis of co-polypropylenes; on the basis of a grafted maleic acid anhydride preferably as a lacquer, and/or on a PVC basis preferably as a film, and/or on a butadiene styrene basis preferably as a lacquer, and/or on a Surlyn basis preferably as a coating, and/or a polyethylene basis preferably as a coating, and/or a polyurethane basis preferably as a lacquer, and/or on a polyester basis preferably as a film or lacquer.

Particularly preferred is an embodiment in which the layer system, in addition to the three layers which are previously described, comprises a sealable layer (sealing layer) preferably adjacent to the oxygen scavenger layer. Surprisingly, by the provision of such a sealing layer, a synergetic effect is achieved which further increases the oxygen absorption capacity of the packaging film. Preferably, the sealing layer is used to seal the packaging film either to itself or to a further packaging constituent, in particular a further packaging film which if necessary can be formed like the packaging film previously described.

To avoid delamination effects it may be advantageous to provide, between the oxygen scavenger layer and the sealing layer, an adhesion improvement layer which is preferably directly adjacent to the said layer. The adhesion improvement layer can be formed on the basis of the chemical compounds disclosed above in connection with the adhesion improvement layer between the barrier layer and the oxygen scavenger layer. With a layer system of aluminium (barrier layer)—adhesion improvement layer—oxygen scavenger layer—adhesion improvement layer—sealing layer, in comparison with a layer system without a sealing layer and without additional adhesion improvement layer, an increase in oxygen absorption capacity of around 41% can be achieved to 152 cm³O₂/g, wherein the weight figure in grammes [g] relates to the oxygen scavenger layer.

It is particularly preferred if, to optimise the barrier properties in relation to oxygen, the barrier layer is formed as a metal layer. Particularly preferably, this is an aluminium-containing layer, suitably an aluminium layer, preferably an aluminium foil, comprising aluminium or an aluminium alloy. Alternatively, the barrier layer can be formed on a steel basis.

Additionally or alternatively, it is possible to form the barrier layer on the basis of a substrate such as a plastic, in particular a plastic film, for example of polyesters such as polyethylene terephthalates (PET), polyamides (PA) etc., with a barrier layer on at least one of the surfaces of the film. Ceramic layers which are deposited physically or chemically or sol-gel layers can be used as the barrier layer.

Ceramic layers can for example take the general formula SiO_(X), wherein x is a number from 1.1 to 2.0, suitably a number from 1.5 to 1.9 and preferably a number from 1.5 to 1.8, or the general formula Al_(y)O_(z), wherein y:z=0.5 to 1, suitably y:z=0.6 to 0.7, or preferably y is the FIG. 2 and z the FIG. 3.

Physically deposited ceramic layers (PVD layers) can be obtained for example by processes of thin layer vacuum technology, by vaporising target materials in the vacuum and depositing the vaporised materials on the plastic film to form the ceramic layer. The ceramic layers can for example have a thickness of 10 to 2000 nm (nanometres).

Chemically deposited ceramic barrier layers (CVD layers) can for example be created from a solution of perhydropolysilazane (PHPS) which is applied to the surface to be coated and then hardened to form a silicon oxide layer (SiO_(x)). Such layers can be combined with PVD layers.

Sol-gel coatings can be produced by means of cross-linkable organo-functional silanes which are obtained with a metal compound, for example by hydrolytic condensation, where applicable in the presence of a condensation catalyst, wherein the coating solution can be applied to a substrate and then hardened.

It is also possible (additionally or alternatively) to form the barrier layer as a laminated film with at least one polymer having a barrier effect or barrier properties. For example the following layer systems can be achieved:

-   -   polyolefin, polyester or polyamide/EVOH/polyolefin, polyester or         polyamide     -   polyolefin/polyamide/polyolefin     -   polyolefin/PVdC/polyolefin     -   polyolefin/polyacrylonitrile/polyolefin     -   polyester or polyamide/EVOH

The individual layers of such laminated films can be present as non-oriented, mono-oriented or bi-oriented films.

The invention also leads to a packaging, in particular a foodstuff packaging, a pharmaceutical packaging or a cosmetic packaging. The packaging is characterised in that it is produced using at least one of the packaging films formed according to the concept of the invention.

Particularly preferably, the packaging is a blister packaging with a cover film sealed to a base film, wherein either the cover film or the base film, or the cover film and the base film, is/are formed according to a packaging film produced according to the concept of the invention. It is preferred if the cover film comprises or consists of a layer system described above, wherein it is particularly preferred if the oxygen scavenger layer is arranged on the flat side of the barrier layer facing the packed product, wherein evidently the adhesion improvement layer is held between the barrier layer and the oxygen scavenger layer in the form of a sandwich. In this way it is possible for the oxygen scavenger layer, in particular if this is sealable, to have direct contact with the packaging inner volume and/or the packed product. In the case of provision of a separate sealing layer adjacent to the oxygen scavenger layer, this preferably has direct contact with the packaging inner volume or packed product.

With regard to the formation of the base film, there are different possibilities—as described above, this can be formed as a packaging film formed according to the concept of the invention. Alternatively, it is possible for the base film to be formed as a laminated film comprising a barrier layer which is active against oxygen and/or a PVC layer and/or an ortho-phthaldialdehyte layer (oPA layer), preferably in the order stated above.

The invention also leads to a packaging-packed product unit. This is characterised by at least one packed product packed in the packaging described above. Preferably the packed product is a foodstuff, a pharmaceutical product, in particular a medicament, or a cosmetic product.

The invention leads to the use of a packaging film formed according to the concept of the invention for production of a packaging, in particular a blister pack. Particularly preferably, the packaging film is used as a cover and/or base film of the blister pack.

Further advantages, features and details of the invention arise from the description below of preferred embodiment examples and with reference to the drawings. These show:

FIG. 1 in a diagrammatic view, a first embodiment example of a packaging film without separate sealing layer;

FIG. 2 a further embodiment example of a packaging film with a sealing layer adjacent to an oxygen scavenger layer, and

FIG. 3 a packaging formed as a blister pack and produced with a packaging film, wherein the packaging film forms the cover film of the blister pack.

In the figures the same elements and elements with the same function are marked with the same reference numerals.

FIG. 1 shows a packaging film 1. This comprises an outer barrier layer 2 of aluminium, on the top in the drawing plane, which prevents the permeation of oxygen from the outside. Immediately next to the barrier layer 2 is arranged an adhesion improvement layer 3 parallel to the barrier layer 2, wherein the adhesion improvement layer 3 can be produced either by treating the barrier layer 2 or by the application of a separate layer on the barrier layer 2. Immediately adjacent to the adhesion improvement layer 3 is an oxygen scavenger layer 4, the purpose of which is to eliminate, in particular bond, the oxygen which is present in the interior of the packaging and oxygen penetrating into the interior of the pack. Particularly preferably, the oxygen scavenger layer is formed as in one of the examples described in WO 2007/051860 A1.

The packaging film 1 in the embodiment example in FIG. 1 consists of a layer system 5 comprising the outer barrier layer, adjacent to this and parallel to the barrier layer 2 an adhesion improvement layer 3, and adjacent to this and parallel to the adhesion improvement layer 3 an oxygen scavenger layer 4 which, in the packaging which is produced with the packaging film 1, preferably faces the packed product directly. The layer system 5 is thus formed as a sandwich wherein the barrier layer 2 and the oxygen scavenger layer 4 hold the adhesion improvement layer 3 between them.

FIG. 2 shows an alternative packaging film 1. The layer system of the packaging film 1 comprises, as well as the layers shown in FIG. 1 and described above, a sealable sealing layer 6 which is directly adjacent to the oxygen scavenger layer 4. An embodiment is also possible in which between the oxygen scavenger layer 4 and the sealing layer 6 is provided a further adhesion improvement layer to improve the adhesion of the sealing layer 6 and the oxygen scavenger layer 4. In the embodiment example shown, the provision of such a further adhesion improvement layer has been deliberately omitted.

FIG. 3 shows a packaging 7 formed as a blister pack. This consists of a cover film 8 sealed to a base film 9. The cover film 8 can for example be formed as shown in FIG. 1 or FIG. 2. A dotted line 10 indicates that the sealing layer 6 can be provided optionally, in particular for the case that the oxygen scavenger layer 4 is not sealable. The outer aluminium-containing barrier layer is also shown, with the adhesion improvement layer 3 directly adjacent thereto and the oxygen scavenger layer 4 directly adjacent thereto, against which layer is the optional sealing layer 6, using which the cover film 8 (packaging film 1) is sealed to the base film 9 in the edge areas 11 which are outside the cavities 12 formed in the base film 9 to receive the packed product not shown, in particular foodstuffs, pharmaceutical products or cosmetic products.

In the embodiment example shown, the base film 9 is formed as a three-layer film which is indicated on the left in the drawing plane. The base film 9 consists of an inner PVC layer 13 facing the packed product. Immediately adjacent on its outside is an aluminium layer 14 as a barrier layer which is covered on the outside by an oPA layer 15.

FIG. 3 indicates by way of arrows that oxygen (O₂) cannot penetrate the packaging film 1 (cover film 8) from the outside (because of the effect of the barrier layer 2). It is also evident that oxygen which is dissolved in the inner volume of the packaging 16 or in the packed product can where applicable penetrate through the sealing layer to the oxygen scavenger layer 4 and is bonded there. Any oxygen which is also permeating through a sealing seam between the cover film 8 and the base film 9 into the interior of the packaging 16 also takes this route. 

1. A packaging film comprising a layer system with a barrier layer preventing oxygen penetration, an adhesion improvement layer adjacent to the barrier layer and an oxygen scavenger layer adjacent to the adhesion improvement layer.
 2. A packaging film according to claim 1, wherein the oxygen scavenger layer is formed from a lacquer material.
 3. A packaging film according to claim 2, wherein the lacquer material comprises a matrix of at least one at least partly organic polymer and at least one component selected from components which after suitable triggering scavenge oxygen.
 4. A packaging film according to claim 1 wherein the adhesion improvement layer is selected from the group consisting of a polyurethane primer layer, an acrylic resin primer layer, an ethylene acrylic acid polymer layer, an extrusion-coated polymer layer, an ionomer resin layer, a plasma treatment layer, a corona treatment layer, a PVD layer, a CVD layer, and a sol-gel layer.
 5. A packaging film according to claim 1 wherein the layer system comprises a sealing layer.
 6. A packaging film according to claim 5, wherein between the sealing layer and the oxygen scavenger layer is provided an adhesion improvement layer.
 7. A packaging film according to claim 1 wherein the barrier layer is formed as a metal layer.
 8. A packaging comprising at least one packaging film according to claim
 1. 9. A packaging according to claim 8, wherein the packaging is formed as a blister pack with a cover film, which is sealed to a base film comprising cavities to seal the cavities.
 10. A packaging according to claim 9, wherein the base film is formed as a laminated film comprising a barrier layer and/or a PVC layer and/or an oPA layer.
 11. A packaging-packed product unit with a packed product, packed in a packaging according to claim
 8. 12. A method for producing a packaging, comprising using a packaging film according to claim
 1. 13. A packaging film according to claim 3, wherein the matrix contains one or more inorganic organic hybrid polymers.
 14. A packaging film according to claim 3, wherein the matrix contains at least one component selected from components which after suitable triggering by radiation scavenge oxygen.
 15. A packaging film according to claim 5, wherein the sealing layer is adjacent to the oxygen scavenger layer.
 16. A packaging film according to claim 1, wherein the barrier layer is formed as an aluminium layer.
 17. A packaging according to claim 9, wherein the cover film is formed by the packaging film.
 18. A packaging-packed product unit according to claim 11, wherein the packed product is at least one foodstuff or at least one pharmaceutical product.
 19. A packaging according to claim 9, wherein the packaging is a blister pack.
 20. A packaging according to claim 9, wherein the packaging is a blister pack and the packaging film is used as at least one of the cover film or the base film. 